Fe-doped Bi2SeO5 nano material as well as preparation method and application thereof

Abstract

The invention discloses a Fe-doped Bi2SeO5 nano material as well as a preparation method and application of the Fe-doped Bi2SeO5 nano material. The preparation method comprises the following steps: dissolving ferric chloride hexahydrate, bismuth nitrate pentahydrate and sodium selenite according to a specific ratio by using a hydrothermal synthesis technology and taking pure water as a solvent, and stirring at the room temperature of 25 DEG C until a system is uniform, so as to obtain a precursor mixed solution of the Fe-doped Bi2SeO5 nano material; the mixed solution is subjected to a hydrothermal reaction and then is subjected to heat treatment in an air atmosphere, and the target Fe-doped Bi2SeO5 nano material is finally obtained by regulating and controlling parameters such as a precursor ratio, a hydrothermal reaction temperature, heat preservation time and heat treatment conditions through a system. The nano material is used for catalytic degradation of antibiotics in a PMS system, and has the characteristics of strong anti-interference capability, good tolerance to acid and alkali environments, remarkable catalytic effect, high stability and the like.

Description

Technical Field

[0001] This invention relates to the field of new materials development technology for wastewater treatment, and in particular to an Fe-doped Bi2SeO5 nanomaterial, its preparation method, and its application. Background Technology

[0002] Antibiotics are widely used because they effectively inhibit bacteria and prevent infections. However, humans and animals metabolize antibiotics at extremely low rates; typically, 25% to 85% of antibiotics remain in their parent compound form or are converted into metabolites and excreted through feces or urine. Therefore, large amounts of antibiotics have been detected in sewage and rivers. Although antibiotics possess certain antibacterial properties, they are difficult to degrade in the natural environment. Moreover, antibiotics accumulate in animals along the food chain and further accumulate in humans, ultimately posing a serious threat to human health. Therefore, the remediation of antibiotics in aquatic environments is extremely important. However, traditional physical methods usually only transfer antibiotics from water to other media (such as adsorbents and membrane materials) rather than truly degrading them, failing to fundamentally eliminate pollutants. Traditional biological methods are highly dependent on environmental factors (temperature, pH, dissolved oxygen, etc.) and have limited degradation capabilities. Traditional ozone oxidation may cause secondary pollution. Therefore, developing a nanomaterial with strong catalytic performance and material stability, and using the economically stable persulfate (PMS) advanced oxidation technology to synergistically degrade antibiotics, has become a clean, efficient, and green alternative technology.

[0003] Advanced oxidation technologies (AOPs) are relatively innovative and efficient in treating antibiotics and exhibit unique advantages in water treatment, utilizing visible light to gradually mineralize pollutants into water and carbon dioxide. Among these, the PMS-AOPs process, based on persulfate (PMS), has a wide range of applications and can be used to degrade various recalcitrant organic pollutants. Studies have confirmed that multiple active species participate in the removal of target pollutants, including sulfate radicals (SO42-). - ·), hydroxyl radical (·OH), superoxide radical (O2) - In addition to free radicals such as ·, singlet oxygen ( 1 Non-radical substances such as O2, high-valence metal-oxide species (HVMO), and electron transfer processes (ETP) also play an important role. [12-13]Among these, the rational design and modification of nanomaterials are the core of catalytic technology. Among numerous catalytic materials, Bi₂SeO₅ possesses advantages such as a unique electronic structure, high photogenerated carrier separation efficiency, low toxicity, and environmental friendliness, making it a key research focus in the field of photocatalysis. However, bismuth-based nanomaterials are wide-bandgap semiconductors, only responding to a relatively short blue light region in the visible spectrum, and cannot utilize red or near-infrared light, thus limiting their utilization of solar energy. Although bismuth-based materials have a built-in electric field, the single material's response to electrons (e... - ) and holes (h + The loading rate of ions remains high; secondly, the degradation of pollutants mostly occurs in the "bond breaking to generate intermediate products" stage, resulting in low mineralization. These issues have become key bottlenecks in the catalytic performance of Bi-based materials.

[0004] To enhance the catalytic performance of Bi, researchers have modified bismuth-based materials using strategies such as heterostructure construction, Bi self-loading, and morphology control. These methods have yielded significant progress at the macromolecular level. However, while these methods can improve catalytic performance, heterostructure construction still suffers from problems such as weak interfacial bonding, easy shedding during cycling, and high cost; and difficulty in controlling the loading amount of Bi self-loading, leading to poor stability under acidic conditions. These challenges prevent the achievement of low-cost, high-performance solutions. In summary, there is still much room for exploration in the study of metal doping to regulate the electronic structure of Bi2SeO5 lattice. The following problems need to be solved: (1) Although Bi-based materials have unique layered structures and electronic properties, most existing technologies still have problems in terms of performance regulation, nanomaterial ratio, and structural stability; (2) Bi-based materials have a fast photogenerated electron-hole loading rate in photocatalysis. Even after modification and optimization, the visible light utilization rate is still low and the surface catalytic reaction is slow; (3) Although metal doping can introduce defects to capture charge carriers, the range of dopable materials is narrow and limited, and the doping amount is also affected. Excessive doping can easily lead to the agglomeration and precipitation of nanoparticles, while insufficient or insufficient doping can cause the modification to fail; (4) The problem of poor tolerance to acid and alkali environments is prominent, and the problem of easy decomposition at high temperatures is also prominent; (5) There is a lack of DFT calculation and characterization analysis.

[0005] Therefore, in view of the above limitations, how to innovate and achieve breakthroughs, modify Bi-based materials by designing low-cost metal doping and elucidating their degradation mechanism for organic pollutants, is particularly urgent from the perspective of research and application value. This is to overcome the current limitations, promote the low-cost, high-value development of bismuth-based materials, and address the dual threat of organic pollutants to humans and the aquatic environment. Summary of the Invention

[0006] The purpose of this invention is to provide an Fe-doped Bi₂SeO₅ nanomaterial, its preparation method, and its application, aiming to overcome the defects and shortcomings of the prior art.

[0007] The technical solution provided by this invention is as follows: A method for preparing Fe-doped Bi₂SeO₅ nanomaterials, the method comprising the following steps: (1) Add 3 mmol of bismuth nitrate pentahydrate and 2 mmol of sodium selenite to 50 mL of deionized water in sequence, stir vigorously until completely dissolved, adjust the pH to 3, and keep stirring vigorously to obtain suspension A; (2) Add 1-3 mmol of ferric chloride hexahydrate to 30 mL of deionized water, adjust the pH to 11, stir, and obtain suspension B; (3) Slowly add suspension B to suspension A, stir continuously for 1 h, put it into a reaction vessel containing polytetrafluoroethylene, and keep it at 200℃ for 12 h; collect the solid product by centrifugation, and wash and dry it in sequence to obtain Fe-doped Bi2SeO5 nanomaterial precursor. (4) The precursor was calcined in air at 300°C for 2 h to obtain Fe-doped Bi2SeO5 nanomaterials.

[0008] Preferably, in step (1), 0.1 mol L is slowly added. -1 The pH was adjusted to 3 with sodium hydroxide.

[0009] Preferably, in step (2), 1 mol L -1 The pH was adjusted to 11 with sodium hydroxide.

[0010] Preferably, in step (3), the washing is performed by washing three times with deionized water and anhydrous ethanol respectively; the drying is performed by drying in an oven at 60°C for 12 hours.

[0011] Preferably, in step (2), 2 mmol of ferric chloride hexahydrate is added to 30 mL of deionized water.

[0012] This invention further discloses the Fe-doped Bi₂SeO₅ nanomaterials prepared by the above method.

[0013] This invention further discloses the application of the above-mentioned Fe-doped Bi2SeO5 nanomaterials in the degradation of antibiotics.

[0014] Preferably, the antibiotic is tetracycline.

[0015] This invention overcomes the shortcomings of existing technologies and provides an Fe-doped Bi₂SeO₅ nanomaterial, its preparation method, and its application. The invention utilizes hydrothermal synthesis technology, using pure water as a solvent to dissolve ferric chloride hexahydrate, bismuth nitrate pentahydrate, and sodium selenite in a specific ratio. The mixture is stirred at 25°C until homogeneous, yielding a precursor mixture for the Fe-doped Bi₂SeO₅ nanomaterial. This mixture undergoes a hydrothermal reaction, followed by heat treatment in an air atmosphere. By systematically controlling parameters such as the precursor ratio, hydrothermal reaction temperature, holding time, and heat treatment conditions, the target Fe-doped Bi₂SeO₅ nanomaterial is finally obtained.

[0016] This invention, through precise control of Fe doping amount and modulation of the electronic structure of the Bi₂SeO₅ lattice, utilizes the adsorption of two terminal oxygen atoms in the persulfate (PMS) molecule, which are connected to the sulfur (S) double bond, onto adjacent Fe-Bi diatomic sites. This diatomic adsorption mode effectively suppresses the breaking of the O-O bond and enhances electron rearrangement, thus achieving a highly efficient and selective electron transfer pathway (RTP). It is worth emphasizing that the electron transfer process (ETP) exhibits significant advantages: not only is the pollutant removal rate faster, but the amount of toxic byproducts generated is also lower, and the oxidant consumption level is lower. Furthermore, it maintains good tolerance to a wide pH range and different water quality matrices. These characteristics make it highly promising for practical wastewater purification applications.

[0017] Compared with existing technologies, the innovation of this invention lies in: (1) This invention achieves efficient electron transfer by adsorbing oxygen atoms connected to the sulfur double bond in PMS at the Bi-Fe dual sites in Fe-doped Bi2SeO5 nanomaterials. This solves the problems of high photogenerated electron-hole recombination rate and slow surface catalytic reaction in Bi-based materials, and effectively regulates the PMS adsorption mode, reducing the quenching interference of water impurities on (reactive oxygen species) ROSs. This nanomaterial has a wide pH adaptability (pH=1~11), breaking the dependence of traditional Fenton or free radical-dominated PMS systems on acidic environments, and is effective in adsorbing Cl in actual wastewater. - PO4 3- It exhibits strong tolerance to coexisting ions, while overcoming the shortcomings of poor acid and alkali tolerance and easy decomposition at high temperatures of Bi-based materials alone. (2) This invention employs a hydrothermal-calcination method to precisely control the morphology of Bi-based materials by adjusting the Fe doping ratio, successfully preparing Fe-Bi2SeO5 nanomaterials with different iron doping ratios. This preparation strategy not only solves the problems of limited doping range, nanoparticle aggregation and precipitation, and modification failure in Bi-based materials, but also selects Fe, which is abundant and inexpensive, as the doping metal, significantly reducing the preparation cost of nanomaterials compared to noble metals such as Pt and Ru, thus combining practicality and economy. (3) This invention utilizes Fe-doped Bi2SeO5 nanomaterials to exhibit efficient degradation capabilities and enhance the mineralization capabilities of organic pollutants, thereby thoroughly degrading organic pollutants into inorganic small molecules: water (H2O) and carbon dioxide (CO2), completely transforming difficult-to-degrade organic pollutants into naturally occurring, non-toxic substances.

[0018] The beneficial effects of this invention after adopting the above technical solution are as follows: (1) The core innovation of this invention lies in the precise control of the structure of nanomaterials and PMS adsorption mode to achieve PMS activation dominated by near electron transfer (ETP), breaking through the limitation of coexistence of free radicals and non-free radicals in traditional catalytic systems. (2) Breakthrough optimization of catalytic mechanism: For the first time, Fe-Bi2SeO5 coordination structure nanomaterials were constructed, and PMS dual-site adsorption was achieved through bimetallic sites. This solved the problems of ETP selectivity dependence on target pollutants and susceptibility to water matrix interference in traditional systems, and achieved stable catalysis under pH (1~11) and complex water quality conditions; (3) The overall improvement in catalytic performance solves the problem of poor tolerance of Bi-based materials to acid and alkali environments. Significantly enhanced practical value; strong anti-interference ability; common in water (Cl... - SO4 2- (etc.) and humic acid have no significant impact on the catalytic effect; it has outstanding stability and economy; it still maintains high activity after 5 cycles of use, and the PMS utilization rate is as high as 98%. Attached Figure Description

[0019] Figure 1 The comparison shows the catalytic degradation kinetics of tetracycline (TC) by pristine Bi2SeO5 and Bi2SeO5 nanomaterials with different Fe doping ratios. Figure 2 The effect of different active species quenchers on TC degradation rate; Figure 3 The effect of recycling Fe-Bi2SeO5 (1:1) nanomaterials on the degradation rate of TC. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0021] Example 1 (1) At room temperature, 3 mmol of bismuth nitrate pentahydrate and 2 mmol of sodium selenite were added sequentially to 50 mL of deionized water and stirred vigorously until completely dissolved. Then, 0.1 mol L⁻¹ of sodium selenite was slowly added. -1 Adjust the pH to 3 with sodium hydroxide, and keep stirring vigorously to form suspension A; (2) At room temperature, add 2 mmol of ferric chloride hexahydrate to 30 mL of deionized water, and use 1 mol L... -1 Adjust the pH to 11 with sodium hydroxide, stir, and form suspension B; (3) Suspension B was slowly added dropwise to suspension A and stirred continuously for 1 h. Then, it was immediately placed into a reaction vessel containing polytetrafluoroethylene and kept at 200 °C for 12 h. After the reaction was completed, the solid product was collected by centrifugation and washed three times with deionized water and anhydrous ethanol to remove impurities. Then, it was dried in an oven at 60 °C for 12 h to obtain the Fe-doped Bi2SeO5 nanomaterial precursor. (4) The precursor was calcined at 300°C for 2 h in air atmosphere to obtain Fe-Bi2SeO5 (1:1) nanomaterial sample with optimal ratio.

[0022] Example 2 This Example 2 is the same as Example 1, except that in step (2), 1 mmol of ferric chloride hexahydrate is added to 30 mL of deionized water, and Fe-Bi2SeO5 (0.5:1) nanomaterial sample is finally obtained.

[0023] Example 3 Example 2 is the same as Example 1, except that in step (2), 3 mmol of ferric chloride hexahydrate is added to 30 mL of deionized water, and Fe-Bi2SeO5 (2:1) nanomaterial sample is finally obtained.

[0024] Example 1 This embodiment uses tetracycline (TC) as the target pollutant to evaluate the performance of its nanomaterials. An accurate concentration of 10 mg / L was prepared. -1Prepare a TC solution. Measure 100 mL of the above contaminant solution into a beaker, and add 35 mg of Fe-Bi₂SeO₅ (1:1) nanomaterials and 30 mg of permonosulfate (PMS) sequentially. Stir for 20 min, and take 3 mL samples at 1, 3, 5, 10, 15, and 20 min of the reaction. Immediately filter the samples through a 0.22 μm organic phase filter membrane to separate the nanomaterials. Collect the filtrate and measure its absorbance using a UV spectrophotometer. To investigate the effect of nanomaterial composition, keep other conditions constant, perform parallel experiments with Fe-Bi₂SeO₅ nanomaterials of different iron doping ratios, and take samples and detect them in the same time sequence.

[0025] Using TC as the target pollutant, the catalytic performance of the prepared nanomaterials was evaluated by PMS. The removal rate of TC was negligible with either Bi₂SeO₅ alone or with PMS alone. The precursor Bi₂SeO₅ combined with PMS achieved a TC removal rate of 61%. As expected, Fe-Bi₂SeO₅ (1:1) exhibited the best catalytic performance, reducing TC removal to 80% within ten minutes. Figure 1 (As shown). The low-valence metal (Fe) doping used in this invention is not only green and economical, but also largely solves the problem of limited doping range in Bi-based materials, thus improving the degradation effect of nanomaterials.

[0026] Example 2 A 10 mg / L tetracycline (TC) solution was prepared for later use. 100 mL of the above pollutant solution was placed in a beaker, and 35 mg of Fe-Bi₂SeO₅ (1:1) nanomaterials and 30 mg of PMS were added. To investigate the main active species during the degradation process, the following quenchers were added to the reaction system: tert-butanol (TBA for quenching ·OH) and methanol (MeOH for quenching ·SO₄). - L-histidine (L-His is used for quenching) 1 O2 scavenger) and p-benzoquinone (p-BQ for quenching O2) - (Capture agent); stir for 20 min, and take 3 mL samples from each reaction system (pollutant degradation reaction system containing quencher) at mins 1, 3, 5, 10, 15 and 20 respectively, i.e. filter through a 0.22 μm organic phase filter membrane. Collect the filtrate and measure its absorbance using a UV-Vis spectrophotometer.

[0027] Capture experiments were conducted in the Fe-Bi2SeO5 (1:1) system (e.g.) Figure 2 As shown in the figure, the removal efficiency of TC by adding TBA, p-benzoquinone p-BQ and L-His was slightly inhibited, indicating that hydroxyl radicals (·OH) and superoxide radicals (O2·) were significantly inhibited. - ) and singlet oxygen (1 O2 contributes only a limited amount to the degradation reaction. However, the removal efficiency after adding MeOH is better than the inhibition effect of the previous three, which indicates that hydroxyl radicals (·OH) and sulfate radicals (SO4·⁻) work together; conversely, the reaction process is almost completely inhibited after adding ethylenediaminetetraacetic acid (EDTA), thus indicating that the present invention is dominated by ETP electron transfer.

[0028] Example 3 A 10 mg / L tetracycline (TC) solution was prepared for later use. 100 mL of the above pollutant solution was placed in a beaker, and 35 mg of Fe-Bi₂SeO₅ (1:1) nanomaterials and 30 mg of PMS were added. After stirring for 20 min, 3 mL samples were taken at mins 1, 3, 5, 10, 15, and 20, and immediately filtered through a 0.22 μm organic phase filter membrane to separate the nanomaterials. The filtrate was collected, and its absorbance was measured using a UV-Vis spectrophotometer. After the reaction was completed, Bi-Fe₂O₃ (1:1) was recovered by centrifugation. The centrifuged nanomaterials were then dried and directly used in the next degradation reaction. Five degradation experiments were conducted consecutively in this manner to evaluate its cyclic stability.

[0029] like Figure 3 As shown, the results indicate that the Fe-Bi2SeO5 (1:1) nanomaterial also exhibits good reusability in its catalytic performance. After 5 cycles, the TC removal rate is still above 85%. During multiple PMS activation processes, the catalytic efficiency of the core catalytic sites did not decrease significantly. Its adsorption and activation capacity for PMS and electron transfer efficiency remained at a high level, without showing deactivation characteristics. This indicates that the nanomaterial of the present invention has strong stability.

[0030] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing Fe-doped Bi₂SeO₅ nanomaterials, characterized in that, The method includes the following steps: (1) Add 3 mmol of bismuth nitrate pentahydrate and 2 mmol of sodium selenite to 50 mL of deionized water in sequence, stir vigorously until completely dissolved, adjust the pH to 3, and keep stirring vigorously to obtain suspension A; (2) Add 1-3 mmol of ferric chloride hexahydrate to 30 mL of deionized water, adjust the pH to 11, stir, and obtain suspension B; (3) Slowly add suspension B to suspension A, stir continuously for 1 h, put it into a reaction vessel containing polytetrafluoroethylene, and keep it at 200℃ for 12 h; collect the solid product by centrifugation, and wash and dry it in sequence to obtain Fe-doped Bi2SeO5 nanomaterial precursor. (4) The precursor was calcined in air at 300°C for 2 h to obtain Fe-doped Bi2SeO5 nanomaterials.

2. The method as described in claim 1, characterized in that, In step (1), 0.1 mol L is slowly added. -1 The pH was adjusted to 3 with sodium hydroxide.

3. The method as described in claim 1, characterized in that, In step (2), 1 mol L -1 The pH was adjusted to 11 with sodium hydroxide.

4. The method as described in claim 1, characterized in that, In step (3), the washing is performed by washing three times with deionized water and anhydrous ethanol respectively; the drying is performed by drying in an oven at 60°C for 12 hours.

5. The method as described in claim 1, characterized in that, In step (2), 2 mmol of ferric chloride hexahydrate is added to 30 mL of deionized water.

6. Fe-doped Bi₂SeO₅ nanomaterials prepared by the method according to any one of claims 1 to 5.

7. The application of the Fe-doped Bi₂SeO₅ nanomaterial according to claim 6 in the degradation of antibiotics.

8. The application as described in claim 7, characterized in that, The antibiotic in question is tetracycline.

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